Electrode assembly, method for manufacturing the same and secondary battery

Abstract

An electrode includes a first electrode and a second electrode alternately stacked with a separator therebetween. The first electrode a first-a electrode and a first-b electrode, in which electrode active material layers have thicknesses different from each other.

The invention claimed is: 
     
         1 . An electrode assembly, comprising:
 a first electrode having a first electrode active material layer and a second electrode having a second electrode active material layer are alternately stacked with a separator therebetween,   wherein the first electrode comprises a plurality of first-a electrodes and a plurality of first-b electrodes, in which the first electrode active material layer of each first-a electrode is thicker than the first electrode active material layer of each first-b electrode,   wherein each first-a electrode and each first-b electrode comprise a first-a electrode tab and a first-b electrode tab, respectively,   wherein the first-b electrode tab has a width greater than a width of the first-a electrode tab,   wherein the first-a electrode tab and the first-b electrode tab do not overlap in a stacking direction,   wherein the first-b electrode tab and the first-a electrode tab are bonded to a first electrode lead,   wherein the first-b electrode tab and the first-a electrode tab are respectively bonded to a first side and a second side of the first electrode lead without being in direct contact with each other,   wherein the first electrode lead has a first section having a width equal to a greatest width between a side edge of the first-b electrode tab and a side edge the first-a electrode tab and a second section having a width less than the first section, and   wherein a number of the plurality of first-a electrodes is twice a number of the plurality of first-b electrodes.   
     
     
         2 . The electrode assembly of  claim 1 , wherein the first electrode active material layer of each first-a electrode and the first electrode active material layer of each first-b electrode have the same area. 
     
     
         3 . The electrode assembly of  claim 1 , further comprising:
 a second electrode lead, to which a second electrode tab of the second electrode is bonded.   
     
     
         4 . The electrode assembly of  claim 1 , wherein the first electrode further comprises a first-c electrode having a same area as each of the first-a electrodes and the first-b electrodes and having a first electrode active material layer, which has a thickness different from that of the first electrode active material layer of each of the first-a electrodes and the first-b electrodes, and
 wherein the first electrode active material layer of the first-c electrode has a thickness less than the thickness of the first electrode active material layer of the first-b electrodes.   
     
     
         5 . The electrode assembly of  claim 4 , wherein the first-c electrode comprises a first-c electrode tab, and
 wherein the first-c electrode tab has a width greater than the width of the first-b electrode tab.   
     
     
         6 . A method for manufacturing an electrode assembly, the method comprising:
 a first electrode manufacturing step of manufacturing a first electrode comprising a plurality of first-a electrodes and a plurality of first-b electrodes, in which electrode active material layers have different thicknesses; and   an electrode assembly manufacturing step of alternately stacking a second electrode and the first-a electrode or the first-b electrode of the first electrode with a separator therebetween to manufacture the electrode assembly,   wherein, in the first electrode manufacturing step, non-coating portions, on which the electrode active material does not exist, of the first-a electrode and the first-b electrode are cut to manufacture a first-a electrode tab and a first-b electrode tab,   wherein the first-b electrode tab has a width greater than a width of the first-a electrode tab and the first-a electrode tab and the first-b electrode tab do not overlap in a stacking direction,   after the electrode assembly manufacturing step, an electrode lead bonding step of bonding the first-a electrode tab and the first-b electrode tab to a first electrode lead and bonding a second electrode tab of the second electrode to a second electrode lead,   wherein the first-a electrode tab and the first-b electrode tab are respectively bonded to a first side and a second side of the first electrode lead without being in direct contact with each other,   wherein the first-b electrode tab and the first-a electrode tab are respectively bonded to a first side and a second side of the first electrode lead without being in direct contact with each other,   wherein the first electrode lead has a first section having a width equal to a greatest width between a side edge of the first-b electrode tab and a side edge the first-a electrode tab and a second section having a width less than the first section, and   wherein a number of the plurality of first-a electrodes is twice a number of the plurality of first-b electrodes.   
     
     
         7 . The method of  claim 6 , wherein the first electrode manufacturing step comprises preparing a plurality of collectors having a same area and changing a loading amount of electrode active material on a surface of each of the plurality of collectors,
 wherein the first-a electrode increases in loading amount of electrode active material compared to the electrode active material of the first-b electrode to manufacture an electrode active material layer having a thickness greater than that of the first-b electrode, and   wherein the first-b electrode decreases in loading amount of electrode active material compared to the electrode active material of the first-a electrode to manufacture an electrode active material layer having a thickness less than that of the first-a electrode.   
     
     
         8 . A secondary battery comprising:
 the electrode assembly of  claim 1 ; and   a case configured to accommodate the electrode assembly.